August 15, 2016

Optimal FV profile in sprint swimmers: more than just another marginal gain?

Unless you were too busy chasing Pokemons,
you’ve noticed that the Men’s Olympic title on the 50-m freestyle was a 0.01s
story. Relatively speaking, for a 21.40s effort, this is a 0.05% difference.
Put that into another metric, the difference between gold and silver was about
one inch, about the distance between your middle and little fingers.

We all know elite sport is a world of
“marginal gains”, and among the many possible ways French swimmer Florent
Manaudou and his staff could have chased this 0.05% marginal gain, my point
here is that the starting block push performance could have been improved using
the optimal force-velocity approach we’ve developed over the last years (see
here for a reminder). Of course, many other factors could have been considered. One is having longer fingers of course. But hey, I have a
hammer so sorry, I see nails everywhere…

For this story (any resemblance to reality is pure coincidence) I will take my own
personal FV profile and imagine I’m an Olympic Games finalist chasing for a
0.05% margin in the Final. Note that my points here are based on scientifically
validated methods and research-based evidence, not on my coach (or my own)
« gut feeling and experience ».

Sprint start push-off performance in swimming

Swim start can be considered as an inclined
single all-out push-off during which the swimmer must produce as much impulse
as possible, so that when taking off, his body as the highest velocity possible
to enter the water (in addition to an optimal diving angle). Many papers are available on this topic, an example with this review. Depending on the studies, the overall angle of
push is about 25-30° (we’ll take 30° in our analysis). What all studies agree
on is the fact that 50-m sprint start take-off velocity is a determinant of
final performance.

So should I improve my take-off velocity
through training, then my block phase performance will be better and all other
things being equal, my final time will also be better. Remember I need a 0.05%
improvement.

How to improve push-off performance through “optimized FV training”

Our approach based on individual assessment of
the force-velocity profile and the computation of the individual optimal
force-velocity profile (see here for a practical summary) shows that in theory,
should my training be specifically programmed to reduce my force-velocity
deficit (i.e. the gap between my actual and optimal profiles), then, my
performance (take-off velocity or jump height in the case of vertical jump)
should increase. This theoretical statement has been confirmed very clearly by
experimental results (paper submitted, see the slides of a Congress
presentation here). Briefly, in this study, subjects whose training loads and
program were individually tailored to reduce the FV deficit all improved jump
height, by extremely large magnitudes (by 14% on average for subjects with a 30-60% force deficit, which is ≈300 times the 0.05% I need) whereas only half of the
controls did, and by lower margins. All control subjects followed the same program,
working on all the spectrum of loads, from very high force to very high
velocity, independently from their individual FV imbalance. A
“one-size-fits-all” approach.

So below is my FV profile. The interpretation
is pretty simple: I have a deficit in force (my actual FV profile (black curve)
is 35% below what would be my optimal FV profile for a swimming start (pink
dashed curve). Note that my actual FV profile was computed using Samozino’s
method knowing jump height and total mass in a 5 or 6 loaded jumps protocol
(see previous episodes and our IJSPP paper for details). It only took 20min and
the scientifically validated iPhone app “MyJump”. The optimal FV profile is
computed as the profile maximizing take-off velocity for a given maximal power
output. Since the equation to calculate the optimal profile includes the
push-off angle, we obtain different optimal profiles for vertical jumping (90°)
and swimming sprint start (30°). Although MyJump only considers 90° vertical
jump optimal profile (update in progress) the equation to compute optimal
profile for any angle has been published here. So my objective here is to
reduce this 35% deficit in force and shift my actual FV profile closer to the
optimal for a 30° push-off.

The training program we used on our scientific
experiment in such a case was pretty simple: heavy loads, maximal strength
work, for 9 weeks with 2 sessions a week. In my opinion, any other training dose
(sessions per week, total duration) would result in positive outcomes provided
maximal lower limb strength is stimulated. More research is needed here to
better design training programs (duration, content, etc…) but what we know for
now is that even small training inputs resulted in substantial changes in the
FV profile (decrease in the FV imbalance) and in turn increased push-off
velocity. This resulted in our study in higher jump height, but in the case of
a block phase, the final outcome would be an improved take-off velocity. Just
do it.

On this basis, how can improve MY push-off performance

So my personal testing shows a force deficit, I will have to program a
strength training that includes a majority of very heavy strength exercises for
my lower limbs, and stimulate my maximal force as much as possible. Of course,
taking into account all the other training components and performance
determinants in a balanced and harmonious manner. Training is not an
all/nothing world.

Then, in order to check my personal adaptations to the training program,
I can do the FV testing (about 20min) every two or four weeks to check whether
my responses follow the training predictions. This approach is dynamic and follows my training-induced adaptation. I may also program the duration of this
specific program: short-term high dose or long-term more progressive dose, or
any other combination…

Counterarguments and reasons for not doing it

Although at first sight this analysis and the
training prescription make sense to me (but i'm totally biased), it might not be the opinion of my coach
and S&C staff…here are counterarguments I may have to face, and my responses.

1/ wait, “Doctor”: what do you know about
swimming? Who are you coaching?

Response: *facepalm*

2/ sorry, we usually do not work on lower
limbs maximal strength. Swimmers don’t like it. We think it destroys their
swimming legs technique, plus they prefer upper body strength work.

Response: *double facepalm* + no evidence on
the long-term interference between legs strength training and swimming “technique”. However, evidence clearly show that strength work in the long term induces improvements
in running economy, through a more efficient running “technique”…well ok
running is different from swimming.

3/ you already have a pretty good start, why trying to improve it? You’d
better work on your weaknesses.

Response: the thing here is that my start is ok, but according to the FV
profile diagnosis, the margin for improvement is large and this could become an
even stronger asset. Training philosophy here: should we work on our strengths
and/or weaknesses…

4/ wait, your study does not include elite swimmers, right? So what if
the results you obtained in trained soccer or rugby players differed in elite
swimmers?

Response: I agree, but what if they did not? I would love to see such studies.

Important notes

First, our personal, unpublished observations
show that most young swimmers we tested, and some elite sprint swimmers
actually show a force deficit such as mine, so this approach may very likely apply to
their case. Second, a recent MSc work I followed also shows this kind of force deficit in trained swimmers.

Conclusion

Swimming, and especially the shortest Olympic
distance, is (now) a sport in which technological improvements are very
unlikely or very small (once the body is shaved and piercings removed…),
so a major part of performance improvements will likely result from training
content and periodization (plus of course anatomical/genetical and
pharmacological factors…). This is the reason why we think a better start performance (and in turn a better overall
performance in the 50-m events at least) could result from monitoring the FV profile
and most importantly from putting the conclusions of this diagnosis into
practice and adapt (even a little bit) the training load accordingly. A
diagnosis without a corresponding treatment is a loss of time.

Lot's of interesting things to test with the Sprint here, including what happens when the swimmer hits the water and short thereafter. Also, swimmers are a bit different, they always have to consider muscle mass vs total volume - there is a tradeoff between strength/density and speed!